Disposable absorbent article having a resilient member

ABSTRACT

An absorbent article comprises a liquid permeable topsheet; a liquid impermeable backsheet joined to the topsheet; an absorbent core positioned between the topsheet and the backsheet; and a soft resilient member attached to the absorbent core or outside of the core which will preferentially deform, bend or lift in a predictable manner when lateral pressure is applied to the pad, wherein the resilient member consists of at least two distinct pieces of foam.

This is a divisional of application Ser. No. 08/510,356, filed Aug. 2,1995, now U.S. Pat. No. 5,858,011.

BACKGROUND OF THE INVENTION

The present invention relates to a disposable absorbent article whichallows better shape retention and body contact during the wearingthereof. More particularly, this invention relates to a catamenial padhaving a soft resilient foam member to reduce bunching, densificationand collapse. This invention is intended to also cover incontinentarticles, sanitary napkins and the like wherein reduced bunching and/orbody contact, in addition to comfort, are important to theirperformance.

It is known that conventional catamenial pads or sanitary napkinscomprise a liquid pervious topsheet, a liquid impervious backsheetjoined with the topsheet, and an absorbent core for storing fluidpositioned between the topsheet and the backsheet. Conventional padshowever, have several disadvantages in that when in use, they becomebunched through lateral forces from the legs. In addition, conventionalcellulosic core matrices may collapse and density due to fluid load andbody pressure. The pads thereby become deformed and do not provide areliable fit or coverage to the undergarments.

Prior known pads have included various structures to try to hold theshape of the pad when in use so that it continues to conform to theshape of the user. Patents which include such structures are describedin U.S. Pat. Nos. 4,195,634 to DiSalvo; 4,886,513 to Mason, Jr.; and5,197,959 to Buell. Although these devices provided structures thatcould resist certain types of deformation, the search for improvedabsorbent articles which continue to hold their shape has persisted.

Therefore, it is an object of the present invention to provide adisposable absorbent article which is soft, has a resilient structure,is resistant to wet collapse, and resists densification by bodypressures, thereby retaining the shape and reducing bunching.Furthermore, the resilient structure is designed to further reducebunching and insure sustained body contact of the pad throughpreferential bending or lift of the pad when lateral forces are appliedby the wearer's legs.

SUMMARY OF THE INVENTION

In accordance with the present invention, an absorbent article isprovided which comprises a liquid permeable topsheet; a liquidimpermeable backsheet joined to said topsheet; an absorbent corepositioned between said topsheet and said backsheet; and a softresilient member attached to said absorbent core which willpreferentially deform, bend or lift in a predictable manner when lateralpressure is applied to the pad.

In accordance with a further aspect of the present invention, anabsorbent article is provided which comprises a liquid permeabletopsheet; a liquid impermeable backsheet joined to the topsheet; anabsorbent core positioned between the topsheet and the backsheet, thetopsheet, the backsheet and the core forming a product; a substratebacksheet attached to the product at least on a portion of a peripherythereof; and a soft resilient member positioned between the product andthe substrate backsheet such that the article will preferentiallydeform, bend or lift in a predictable manner when lateral pressure isapplied to the article.

In accordance with still a further aspect of the present invention, amethod of making an absorbent article is provided which comprises thesteps of providing a liquid permeable topsheet; providing a shapedabsorbent core; providing a piece of tissue; providing a first piece ofresilient member having dimensions smaller than the piece of tissue andhaving a top, a bottom and a side edge; adhering the tissue to the topof the resilient member; folding any remaining tissue over the side edgeof the resilient member; cutting at least one additional piece ofresilient member; attaching the at least one additional piece to thefirst piece of resilient member so that the first piece of resilientmember drapes over the at least one additional piece of resilientmember; attaching a liquid impermeable backsheet to the first piece ofresilient member; and sealing the topsheet to the backsheet.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example and with referenceto the accompanying drawings, in which:

FIG. 1A is a top view of a catamenial pad according to the presentinvention.

FIG. 1B is an end view of the catamenial pad of the present invention.

FIGS. 2A-2C are end views of three alternative pad designs.

FIG. 3 shows V-shaped panty fastening adhesives.

FIGS. 4A-4D show simulated elastic-like polymer film which is used in apreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

It is an object of the present invention to provide a catamenial pad orother disposable absorbent article having superior fit and fluidhandling capabilities by the addition of a resilient member which willpreferentially deform, bend, or lift in a predictable manner whenlateral pressure is applied to the pad. The pad will bow upwards tocontact the body upon lateral compression. When the lateral pressure isreleased, the pad will spring back out to approximate its full originalwidth.

As used herein, the term "disposable absorbent article" refers toarticles which absorb and contain body exudates and more specificallyrefers to articles which are placed against or in proximity to the bodyof a wearer to absorb and contain the various exudates which aredischarged from the body (e.g., blood, menses, urine) and which articlesare intended to be discarded after a single use (i.e. they are notintended to be laundered or otherwise restored or reused). A preferredembodiment of the disposable absorbent article of the present inventionwould be used in a sanitary napkin or catamenial pad. As used herein theterm "sanitary napkin" refers to an article which is worn by femalesadjacent to the pudendal region and which is intended to absorb andcontain menstrual fluids and other vaginal discharges.

In the application of the present invention, a disposable absorbentarticle such as a catamenial pad is provided which has a liquid pervioustopsheet, a liquid impervious backsheet, and an absorbent core. Thetopsheet and the backsheet preferably have length and width dimensionsgenerally larger than the absorbent core. They are joined togethereither directly or indirectly through intermediate materials.

The topsheet is compliant, soft feeling, and non-irritating to thewearer's skin. Furthermore, the topsheet is liquid pervious, permittingliquids to readily transfer through its thickness. A suitable topsheetmay be made of a wide range of materials such as formed thermoplasticfilms, apertured plastic films, porous foams, reticulated foams, naturalfibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polyesteror polypropylene fibers) or from a combination of natural and syntheticfibers with formed films being preferred. Suitable nonwoven topsheetscan be an 18 g/yd² (21.5 g/m²) spunbonded polypropylene nonwovenmaterial known as CELESTRA available from Fiberweb, North America ofSimpsonville, S.C., which is then embossed with the pattern described inU.S. Pat. No. 4,781,710 issued to Megison, et al. on Nov. 1, 1988; orthe resilient plastic web known as Dri Weave, a plastic apertured formedfilm such as the macroscopically expanded three-dimensional, resilientplastic web exhibiting a fiber-like appearance and tactile impressionmade in accordance with U.S. Pat. Nos. 4,342,314 and 4,463,045.

Formed films are preferred for the topsheet because they are pervious toliquids and yet non-absorbent. Thus, the surface of the formed film,which is in contact with the body, remains dry, thereby reducing bodysoiling and creating a more comfortable feel for the wearer. Inaddition, the topsheet is sprayed with a surfactant in order to create ahydrophilic surface which helps transfer liquid through the topsheetfaster.

The backsheet material is preferably a thin plastic film, though otherflexible liquid impervious materials may also be used. The backsheetprevents the exudates absorbed and contained in the core from wettingarticles which come into contact with the pad such as pants, pajamas orundergarments. The backsheet thus may comprise a woven or nonwovenmaterial, a polymeric film such as thermoplastic films of polyethyleneor polypropylene, or composite materials such a film-coated nonwovenmaterial. An exemplary backsheet material is a 1 mil thick (onethousandth of an inch or 0.025 mm) polyethylene film.

The absorbent core may be formed of any means which is generallycompressible, conformable and non-irritating to the wearer's skin, andcapable of absorbing and containing liquids and certain body exudates.The absorbent core may be formed in a variety of sizes and shapes (e.g.,rectangular, hourglass, etc. as is known in the art) and formed from awide variety of liquid absorbent materials commonly used in disposablesanitary napkins, diapers and other absorbent articles, such ascomminuted wood pulp. This type of wood pulp is generally referred to asairfelt and is utilized in the preferred embodiment of the presentinvention. Examples of other suitable materials for the absorbent coreinclude cellulosics such as chemically altered cellulosic, thermallybonded cellulosic, superabsorbent hydrogel forming polymer materialswhich swells when wet (which may, therefore, also be referred to hereinas absorbent gelling material or "AGM")--laminates, synthetics, orcombinations thereof. Other examples include creped cellulose wadding,absorbent hydrogel materials, polymeric fibers, or any equivalentmaterials or combinations of materials.

Superabsorbents are materials which are capable of absorbing body fluidin quantities corresponding anywhere from several times to 60 timestheir own weight. The total absorbent capacity of the absorbent coreshould, however, be compatible with the design exudate loading for theintended use of the absorbent article. Furthermore, the size andabsorbent capacity of the absorbent core may be varied to accommodatethe wearer's size and also ranging in the expected amount of exudatefluid volume. For instance, a different absorbent capacity may beutilized for sanitary napkins intended for daytime use as compared withthose intended for nighttime use, or for sanitary napkins intended foruse by teenage females as compared with those intended for use by moremature women.

The absorbent article of the present invention utilizes a resilientmember in order to provide better shape retention and body contact. Byusing a soft, resilient member with preferential bending or lift, a thin(less than 10 mm caliper and preferably less than 4 mm) absorbent corecan be made to provide a catamenial pad which retains its shape, reducesbunching, gives better area coverage and sustains body contact throughuse. The disposable absorbent article of a first embodiment of thepresent invention is comprised of a thin absorbent core attached to aresilient foam member positioned between a fluid permeable topsheet anda fluid impermeable backsheet. The original shape and caliper of thecore is maintained through use, as a result of the soft, resilient foammember. The resilient member can be made from natural rubber, preferablya cross-linked natural rubber foam or a synthetic material, such assynthetic rubber foam. The member may be attached to the core withadhesive.

It is very important for the core to be thin in order to bend and movewith the resilient member as well as to compensate for the added bulk ofthe resilient member. The sides of the core are thinner than the centerand little core material extends beyond the periphery of the member sothat only a small area of the pad will be compressed from body pressuresduring use. This prevents bunching of the entire core and loss ofprotection. The use of a cross-linked natural rubber foam (XNRF)resilient member provides the unique set of properties of being veryflexible and soft but also highly resilient.

Optionally, the core and member may have a tissue cover. A piece oflatex bonded airlaid tissue is preferably glued to the foam backbone tohelp keep the core securely attached to the backbone through betterfriction and cohesion. The rubber foam alone is very slick and smooth.As a result, the core may become detached and consequently becomebunched.

In a preferred embodiment of the present invention, the core iscomprised of absorbent gelling material, PET (polyethyleneterephthalate) staple fiber (for resiliency) and cellulosic fiber. Thecore is preferably less than 4 mm, most preferably 3 mm caliper. Thetissue is a piece of airlaid tissue, preferably that available from Ft.Howard of Green Bay, Wis. or Merfin of Vancouver, B.C.

This system will now be described in detail below with respect to thefigures. It is to be understood that the forgoing general descriptionand the following detailed description are exemplary and explanatory butare not to be restrictive of the invention. The accompanying drawingswhich are incorporated in and constitute a part of this invention,illustrate the embodiments of the invention, and, together with thedescription, serve to explain the principles of the invention in generalterms. Like numerals refer to like parts throughout the disclosure.

The product 10, in accordance with FIGS. 1A and 1B, has an hourglassshape. The core 12 is located between the topsheet 13 and the backsheet15 and is profiled in the transverse 14 and the longitudinal 16directions. A two piece resilient member 18 is provided in accordancewith the present invention. The first piece 20 is closest to the core 12and provides full center area coverage. A typical dimension would be 60mm in width×70 mm in length×2.5 mm in thickness. The caliper of thislayer is important so that it is flexible enough to drape over the puck22 in order to achieve preferred deformation and lift when lateralpressure is applied by the legs. The second piece 22 is a narrow puck.It must have sufficient caliper in order to provide good overallsustained body contact. The majority of the pad caliper is comprised ofresilient foam which does not collapse and densify like the current 100%cellulosic core constructions. The puck width must provide the bestlabial fit but not be intrusive. The puck length must be provided suchas not to interrupt gluteal fit (that is, fit in the crevice between thewearer's buttocks). A typical dimension for the puck would be 12 mm inwidth×70 mm in length×7.5 mm in thickness. The core 12 of the pad 10 iswrapped around the resilient member 18 as shown in FIG. 1(b) to create alongitudinal direction and a transverse-direction profile, similar inshape to a pillow. Specifically, if a product is profiled in thelongitudinal direction, it has a thick center and thinner ends. If aproduct is profiled in the transverse direction, it has a thicker centerand thinner sides. This type of profiling improves the absorbency andfit of the product. As stated above, the pad 10 usually includes atissue 24 glued to the backbone 18 to prevent the core form becomingdetached.

The core 12 is preferably made of a blend of cellulosic fibers,absorbent gelling material and PET. The amount of AGM is not as criticalas the amount of PET. Preferably, the core is 60-70% cellulosic fibers,about 20% AGM and 10-20% PET. However, as the PET range approaches 20%the core becomes more hydrophobic. Therefore, 10-12% PET is optimal.

In accordance with the present invention, several modifications may bemade to this embodiment without departing from the scope of theinvention. For example, synthetic rubber foam may be used as areplacement for the XNRF. The dimensions of the insert may be narrowedfor an improved fit or to conform to the shape of a wearer. Also, 3 and4 pieces of foam may be used to build thickness.

As shown in FIG. 3, a V-shaped panty fastening adhesive 42 may be usedfor decoupling the pad 10 for fit at the introitus. In this embodiment,the V-shapes 42 are at both ends of the pad 10 having the pointedportion of the V 44 pointing inward. This is disclosed in WO 93/01783published Feb. 4, 1993, by Olsen et al. entitled "ABSORBENT ARTICLEFASTENER PATTERN".

As a further alternative, a single piece member design may beincorporated in the design of the present invention in place of amultiple piece construction as long as the member will preferentiallydeform, bend or lift in a predictable manner when lateral pressure isapplied.

In addition to cross-linked natural rubber foam and synthetic rubberfoam, numerous types of resilient materials may be used for theresilient member of the pads according to the present invention. Theseinclude, but are not limited to, nonwoven highlofts, synthetic fiberbatts, scrims (oriented, plastic netting which can be made with varyingflexibility) and other forms of foam such as polyurethanes, such asthose shown in U.S. Pat. Nos. 5,260,345; 5,263,224 and 5,331,015.

The process of making an absorbent article according to theabove-embodiment of the present invention will now be described. Example1 describes an absorbent disposable article having a resilientcross-linked natural rubber foam member while Example 2 describes anabsorbent disposable article having a resilient synthetic rubber foammember.

Method Example 1 (XNRF)

A 7×12 inch (17.8×30.5 cm) piece of continuous topsheet material isultrasonically bonded to Spunlace, a type of nonwoven material, for thetopsheet. An approximately 60×205 mm full-sized shaped core having acomposition of 80% airfelt and 20% polyester core blend with 20% a SANWET absorbent gel material from Sumitomoseilca, Osaka, Japan, is diecut. A partial core having the same material as the full-sized core (0.2gram per square inch basis weight) and having the dimensions ofapproximately 60×110 mm is die cut. The partial core is featured intothe bottom of the full line made airfelt core blend making alongitudinal profile of the entire core. The top of the core is thenbonded to the topsheet using about 0.08 g/pad of adhesive.

Next, an approximately 60 mm×70 mm piece of tissue and an approximately52 mm×70 mm piece of 0.1 inch (2.5 mm) XNRF foam are cut. These twopieces are then spirally glued together, the Ft. Howard tissue on top ofthe XNRF foam layer. The extra tissue material is folded over the sidesof the XNRF. Two small pieces of 0.2 inch (5:8 mm) XNRF foam having thedimensions of about 1/2×3 inches (12.7×76.2 mm) are cut out and centeredunder the larger XNRF layer. They are held in place by one inch tape,preferably 3M tape, placed on the bottom of the small XNRF pieces. A0.25 inch (6.35 mm) piece of tape is placed down the side of the largeXNRF foam and taped to a polymeric backsheet. The topsheet/core and foamsubunits are combined before sealing. The resulting pad is die sealed.The pad is then trimmed leaving an approximate 5 mm crimp around itsperiphery. Then an approximately 2×7 inch (50.8×177.8 mm) pantyfastening adhesive is applied to the backsheet. Next, the release paperis applied to the back of the pad. Finally, 0.01 g/pad of surfactant,such as Pegosperse sold by Glyco Chemical, Inc. of Greenwich, Conn., issprayed on the topsheet to make it hydrophilic.

Method Example 2 (Synthetic Rubber Foam)

A first layer of Ft. Howard tissue is cut having the dimensions ofapproximately 52 mm×70 mm (21/16"×23/4"11). Then a top layer of 0.1 inch(2.54 mm) thick rubber foam is cut approximately 52 mm×70 mm(21/16"×23/4"). Next, three layers of 0.1 inch (2.54 mm) rubber foam arecut having the dimensions of approximately 6.35 mm×76 mm (1/4"×3") forthe bottom layer. Glue, such as Findley adhesive, from FindleyAdhesives, Inc. of Elmgrove, Wis., is applied spirally to one side ofthe Ft. Howard tissue and the top layer of 0.1 inch (2.54 mm) rubberfoam is attached. Then a piece of about 70 mm, 7 inch (25.4 mm) doublesided tape is placed down the center of the 0.1 inch (2.54 mm) rubberfoam/tissue on the foam side. The paper backing is removed from the 1inch (25.4 mm) piece of tape. Next, one layer of the 0.1 inch rubberfoam (1/4×3"(6.35×76.2 mm)) is centered onto the 1" tape. One layer of1/4" (6.35 mm) tape is placed on the foam. Then the paper backing isremoved from the tape and another piece of 0.1 inch (2.54 mm) foam isplaced on top of the 1/4" tape. This process is repeated until all threelayers of (1/4"×3"(6.35 mm×76.2 mm)) foam are stacked. Next, a piece of1/4 (6.35 mm) tape is placed down the center of the last 0.1 inch foam.A roll of bonded topsheet is cut into approximately 12" (304.8 mm) rollpieces. The topsheet is the embossed CELESTRA as per U.S. Pat. No.4,781,710, layered with a Dry Weave material, as shown in U.S. Pat. No.4,919,738 to Ball et al., entitled "DYNAMIC MECHANICAL BONDING METHODAND APPARATUS". The topsheet (Dry Weave side down) is placed onto thework surface. Core bonding adhesive, such as Findley H2031- 0.005 g/in²(0.0323 g/cm²), a hot melt adhesive, was applied to the CELESTRA side ofthe topsheet. The release paper is then removed from the adhesive. The64% airfelt, 16% PET (CELWET from Hoescht Celanese), 20% AGM core wasplaced carefully centered on the spiral glue. The synthetic rubber foamunit is placed onto the back side of the core having the Ft. Howardtissue side towards the core. The unit is centered in the longitudinaland transverse directions. The paper backing is removed from the 3pieces of the 1/4" (6.35 mm) tape on the last piece of foam. Apolyethylene backsheet is applied. The pads are then sealed with a die.Panty fastening adhesive having the dimensions of about 2"×3/4" (50.8mm×19.05 mm) is applied in a "V" shaped pattern on white release paper.The pad is then strayed with a surfactant, such as Pegosperse (0.01g/pad). Finally, the article is inspected.

The article had the following finished product dimensions:

    ______________________________________    weight               12.5   g    length               225    mm    center width         76     mm    end width            93     mm    center caliper       20.2   mm    end caliper          8.4    mm    ______________________________________

Besides the above arrangement of a resilient member and puckarrangement, other dimensions of the insert may provide additionalbenefits for fit. For example, the resilient layer could be placedoutside the backsheet and/or enclosed by a layer of polymeric material.Or, the resilient member may be glued to the base for a more secureattachment.

Additionally, products such as a core tube or bun as shown in U.S. Pat.No. 4,425,130 to Des Marais, could be used in conjunction with theresilient member insert. A bun is a tufted bundle of capillary channelfibers that are positioned generally on top of the absorbent core.Products with very flexible ends could be used to enhance fit in thegluteal groove.

For example, in accordance with an alternative embodiment of the presentinvention, the absorbent core may be superimposed onto an adhesive whichis applied to the inner surface of the backsheet and which is intendedto hold the barrier sheet in place on the absorbent core. In thisembodiment, the topsheet extends around the side edges of the absorbentcore and over the barrier sheet where it overlaps itself on the garmentsurface of the napkin so as to completely envelope the element. Theabsorbent core, and the barrier sheet thereby form what is commonlyknown as a "tubular napkin". The overlapping portions of the topsheetand the barrier sheet are heat-sealed to each other to form the endedges of the napkin. Three of these arrangements will be describedhereinbelow and with respect to FIGS. 2A-2C.

In the first arrangement shown in FIG. 2A, the tube 32 comprises theentire pad including the topsheet 33, backsheet 35 and absorbent core37. The tube 32 is attached with double sided tape to a structuralelastic-like polymer film backsheet 34. The polymer film backsheet 34need not provide all of the functions of a backsheet and need not extendthe entire length of the pad. Its purpose is to provide the deformationof the core 37 for improved fit.

Such a structural elastic-like polymer film is defined as shown in FIGS.4A-4D. A web of material 60 is shown having a network 62 of strainableregions formed therein that exhibit an elastic-like behavior in thedirection of elongation without the use of added elastic materials. Twodistinct regions provide the web with a first region 64 of aelastic-like, relatively low resistive force stage and a second region66 of a relatively high resistive force stage. The second region 66includes a plurality of continuous, interconnected deformations 74 whichextend beyond the plane of the first region 64. FIGS. 4B-4D show themanner in which the structural elastic-like polymer strainable webmaterial 60 exhibits at least two significantly different stages ofcontrolled resistive force to elongation when subjected to an appliedelongation.

In the second alternative arrangement, the tube 32 is attached as above.However, in addition, a XNRF resilient member roll 36 is inserted in thetube 32 as seen in FIG. 2B. The XNRF is preferably approximately 5 mmthick and approximately 65 mm in length. The roll 36 may be furthersecured to the polymer film backsheet 34 with glue, if desired. Theresilient member roll 36 is outside of the main backsheet 35 andtherefore, no tissue is required to attach the roll 36 to the core 37.

In the third arrangement, the resilient XNRF roll 36 is inserted in thetube 32 as in the second arrangement above. However, in place of thestructural elastic-like polymer film as a backsheet 34, an approximately2 mm thick layer of XNRF 38 is used, which preferably has the dimensionsof approximately 70 mm by 50 mm, as shown in cross-section in FIG. 2C.

Therefore, it is seen from the above embodiments that the addition of aresilient member 36 enhances the fit and fluid handling capabilities ofa disposable absorbent article.

Having described the invention in detail and by reference to preferredembodiments thereof, it will be apparent that modifications andvariations are possible without departing from the scope of theinvention defined in the appended claims.

What is claimed is:
 1. An absorbent article having a predetermined shapecomprising:a liquid-permeable topsheet; a liquid-impermeable backsheetjoined to said topsheet; an absorbent core positioned between saidtopsheet and said backsheet, wherein said core is adhered to an innersurface of said backsheet such that said backsheet is held in place onsaid absorbent core, said topsheet, said backsheet and said core forminga product; and a substrate backsheet joined to said product at least onopposing longitudinal portions of a periphery thereof forming a cavitybetween said product and said substrate backsheet, said product beingdeformed upwards in a predictable manner when pressure is applied tosaid article by a wearer, and returned to approximate said predeterminedshape when said pressure is released; wherein said substrate backsheetis a structural elastic-like polymer film having a network of distinctstrainable regions formed therein that exhibit an elastic-like behaviorwithout the use of added elastic materials.
 2. The absorbent article ofclaim 1 wherein said article further comprises a resilient member, saidresilient member being rolled and positioned between said product andsaid substrate backsheet wherein said resilient member enhances fit andfluid handling capabilities of said article.
 3. The absorbent article ofclaim 2 wherein said resilient member is a crosslinked natural rubberfoam.
 4. The absorbent article of claim 1 wherein said substratebacksheet is joined to said product using double sided tape.